Hoiv to obtain it. 209 



The red ones ( Arachnida histrionica) look particularly bright 

 and attractive, and trout fry will often turn and follow them, but, 

 for some unexplained reason, they do not seem to eat them. It 

 is well known that some spiders are poisonous, and this may have 

 something to do with the matter. Livingstone Stone says : " If 

 a trout not over two-and-a-half inches long strikes at a black 

 spider in the water, the spider will strike back at him, and if he 

 takes a good aim he will kill the trout instantaneously. The little 

 fellow will not go twelve inches before he turns over on his back, 

 and drops down dead." This is what happens in America. 



It is a pleasure to turn from the mites to the water boatmen. 

 Entomologists speak of the large ones as Notonecta glauca. They 

 are about three-quarters of an inch long, by about hardly a quarter 

 wide, and have two long ciliated oars to swim with, from which 

 they derive their name. The largest yearling trout devour them 

 greedily. The smaller ones fight for them, but the fry stand a 

 poor chance they being the prey of the beetles, who mercilessly 

 harpoon them. Fortunately, although common insects, they do 

 not usually abound in great numbers in trout waters. They 

 delight in the stagnant, or semi-stagnant waters of ponds and 

 ditches, in both the larval and the mature stages. Here, again, is 

 a wonderful provision of nature for the production of a large food 

 supply for the trout, when the latter have grown somewhat. 

 The insects may be cultivated in special ponds, and swept out 

 with a suitable net as required. 



Another genus, the Corixida*, containing some thirty species, 

 must have our attention. Of these Corixa ntlgaris is perhaps the 

 commonest. In general form it very much resembles a Notonecta^ 

 but it swims the other way up ; that is, with the oars underneath, 

 and it is only about a quarter of an inch long. Some members 

 of the genus attain a length of half an inch. They are very 

 pugnacious, and are carnivorous in their habits, eating decaying 

 animal matter, and attacking any living creature that is not strong 

 enough to resist them. They swim by means of rapid strokes of 

 their oars, which gives them a jerky movement. They are air 

 breathers, coming to the top of the water for an instant every few 

 minutes. When the fry are two months old, or even before if 

 vigorous, they hunt coi ixa like a pack of hounds, and eat them 

 p 



